Spring assembly



June 14, 1938. J PURWEET 2,120,528

SPRING ASSEMBLY Original Filed Oct. 12, 1935 INVENTOR JULIUS E. PURWEETv ATTOR;NEY 1 Patented June 14, 1938 UNITED STATES PATENT OFFICEApplication October 12, 1935, Serial No. 44,803 Renewed November 9,1937- 3 Claims.

This invention relates to a spring assembly of the type sometimes calleda draft spring and in which a coiled compression spring is locatedbetween two abutment washers or discs with U- shaped tension membersconnected to each disc and extending axially through the spring inrelatively reversed direction so that oppositely direct pulls on thetension members will place the interposed spring under compression.

Some forms of spring assemblies as heretofore constructed are expensiveto manufacture, among other reasons due to the fact that machine workhas to be performed after the component parts have been assembled atleast to the extent of binding the tension members to clinch them to theabutment disks and where the tension members are slidably mounted in theabutment disks the relatively movable parts must be machined to fit.Further it is usual to secure the free ends of the tension memberspermanentlyone to each of the abutment discs, thus rendering itimpossible to replace the spring therebetween should it become damagedor lose its resiliency.

Accordingly, the primary object of the invention is to provide asimplified form of draft spring assembly which will permit thepreforming of the component parts as complete articles and whichseparately formed parts can be fabricated into the desired assembly evenby unskilled labor and without necessity of using any tools whatsoever.

Springs of this character are very apt to be subjected when in use todistorting strains with the result that jarring actions and the likethereon are quite apt to disarrange the parts from their initially setrelative position. A common complaint against known forms of such springassemblies is that the tension members which following approvedpractices are originally set in planes at right angles to each other,tend to rotate relative to each other about the axis of the spring thustending to disarrange the desired uniform distribution of pressure onthe abutment discs and thus on the spring ends. Accordingly, the presentdisclosure features not only a structure which can be easily fabricatedbut also a construction which acts to maintain the tension members intheir originally prelocated position restrained from the undesired axialrotation. This feature of the invention is attained by forming a pair ofintersecting slots in the abutment disks in the form of a Maltese crossand locating the four sides of the two U-shaped tension members in theslots, one side located in each arm of the slots, the portion ofmaterial between the arms of the slots acting as stops or spacing Stillanother object of the invention featuring ii ease in assembling thecomponent parts is to form the tension members simply as U-shaped bentwires and provide in the proportion of the tension members andassociated compression spring a disposition of parts such that thecrotch end of the U-shaped tension members forms a smooth end which canbe readily threaded axially through the bore of the compression springwithout possibility of loose ends catching in the turns of the springand which tension members when in position will coact with a fairlyclose fit within the spring to form a fairly rigid internal guidetherefore and thus resist lateral distortion of the spring whilepermitting a freedom of axial compression movement.

Various other objects and advantages of the invention will be in partobvious from an inspection of the accompanying drawing and in part willbe more fully set forth in the following particular description of oneform of draft spring embodying the invention, and the invention alsoconsists in certain new and novel features of construction andcombination of parts hereinafter set forth and claimed.

In the accompanying drawing:

Figure l is a view of a draft springassembly constituting a preferredembodiment of the invention and with the right hand abutment disc shownin vertical section;

Figure 2 is a plan view of one of the abutment discs separated from theassembly;

Figure 3 is a view in end elevation looking at the right hand end ofFigure 1, but it is understood that if Figure 3 was rotated it wouldsimilarly illustrate the left hand abutment disc;

Figure 4 is a showing of the draft spring of Figure 1, illustrating astep in its construction at the point where the left hand disc is beingthreaded on to the assembly and before the tension members have beenintercollapsed into the position shown in Figure 1; and

Figure 5 is an end view looking at the left hand end of Figure 4.

In the drawing there is shown a coiled compression spring Hi ofconventional cylindrical form and having its opposite ends II and I2flat to form abutting ends. It is a feature of this disclosure that thespring is not secured to any part and may be replaced in the assemblyreadily by another spring of the same or different dimension. The flatends I and [2 are engaged respectively by abutment discs l3 and M ofidentical construction so that the detailed description of one will besufficient for the other. Each disc is of a flat washer or coin-likeform and is provided centrally thereof with two narrow intersectingslots l5 and I6 centered in the disc and arranged in Maltese cross form.Preferably each disc has a diameter slightly greater than the externaldiameter of the spring I!) to provide a broad bearing engagement betweenitself and the spring turn engaging the same, and is centered relativeto the axis of the spring by two spring compressing tension members Hand I8.

These compression members are of identical form so that here again thedetailed description of one will be sufficient for the other. Eachtension member is simply a length of stiff springy wire bent back uponitself at its midlength to,

form two parallel long straight rod-like sides l9- and 20 connected by aU-forming crotch 2| which has no greater widththan the width of theportion of the member formed by the parallel sides I 9 and 20 and thusno greater width than the internal diameter of the spring Ill. The freeends of each of the sides l9 and 20 is bent outwardly at right angles toform disc face engaging abutments 2| and 22 and then bent at its extremeend back upon itself to form stops which lap the outer edge of theassociated disc. The hooks thus formed are disposed in relativelyoutwardly projecting position in the plane of the associated sides andcrotch to facilitate the threading of the disc on to the hook end asshown at the left end of Figure l. The slots l5 and I6 are soproportioned that their length is equal to the width of the tensionmembers measured between the parallel sides so that the parallel sidesin their normal tendency to spread apart engage in the opposite ends ofthe slot as illustrated in Figure 3. The hooked ends 2| and 22 are soproportioned that their aggregate length when the free ends of thetension members are pressed together in contact with each other asindicated at the left of Figure 4 will just permit the ends to be passedthrough their associate slots. The extreme ends of the hooks are soproportioned and located that they overlap the outer periphery of thedisc as shown at the right hand side of Figure l and thus form a pocketinto which the discs fit more or less snugly.

In assembling the parts it will be noted as by reference to Figure 4that the right hand disc I4 is simply slid on the, at that time free,smooth surfaced crotch end of the member H and moved along the sides I!)and 20 until it engages the hook ends. The spring I0 is then slid on themember ll, the smooth crotch end assisting in threading the tensionmember into the spring. The member I8 is then hooked through the openingat the left end of member I! so that the crotch end of one extendsthrough the crotch end of the other leaving the entire length of member|8 exposed for manual gripping in the succeeding step of threading theleft disc on to the assembly. The free ends of the member l8 are thenpitched together and disc I3 threaded thereon. This is attained bylooping the upper end of disc l3 over the upper hook 2|, lowering thedisc to engage the side H! which action lowers the slot I suificient topermit the lower hook 22 to pass therethrough after which the sides l9and 20 are permitted to spring apart thus locating the sides I9 and 20at opposite ends of the slot l5. "Themembers or |8 are then telescopedaxially one into the other, the crotch end of the member l8 being passedthrough slot l6 of disc l4 and the crotch end of member I! being passedthrough the slot l5 of disc l3 to complete the assembly as shown inFigure 1.

In operation it is understood that outwardly directed axial pull on thecrotches 2| of the two tension members will cause the discs l3 and I4 totend to approach each other and thus place the interposed spring l0under compression as is usual with such forms of draft springs.

Should it be desired to dismantle the parts in order to replace thespring, the operation is simply reversed. By pulling the hooked ends ofthe members relatively away from each other the tension members arerestored to the position shown in Figure 4, and the parts are simplyseparated from each other.

By means of a device of this character, it is possible to quicklyassemble the components parts solely by manual operation and without thenecessity of the usual practice of welding or bending the parts intoposition. The hooked ends offer no difficulty either in assembling ordismantling the parts for it is the smooth crotch ends which are used toreceive the spring and left disc. The Maltese cross arrangement of slotsis of particular importance in that it maintains the members l1 and i8in their prefixed relation in planes at right angles to each other andthus free of relative rotationed movement. Further the structure forms askeleton frame of two pairs of rod-like sides which are held fixed inequidistantly spaced circumferential relation to form a rugged internalguide which tends to maintain the spring in its preformed cylindricalform.

In general there is obtained a particularly rugged compact assemblywhich tends to resist displacement of the parts under vibratory or otherconditions which would otherwise tend to disarrange the parts while inuse.

The present disclosure particularly features a construction in which allof the component parts may be manufactured as stock parts with a fewstandard sizes and from which a large number of different sizeassemblies may be formed at will simply by selecting the desired lengthof spring and tension members to meet the peculiarities of any onesituation and it is obviously within the scope of the disclosure toutilize more than one spring in place of the single spring 20 withseparating washers therebetween and by a judicious selection of springsof different tensions and strengths variable compressive resistances maybe obtained and variable resistances at different stages of thecompressive action.

I claim:-

l. A spring assembly comprising two similar completely preformed wiretension members fixedly disposed in planes extending at right anbles toeach other, each tension member being of U-form having parallel sidesconnected at a crotch end, with the free ends bent relatively outwardfrom each other to form a pair of disc-face engaging abutments and theirextreme ends bent back at right angles to the face engaging abutments toform disc-edge-lapping stops, a coiled compression spring of less lengththan the tension members, having the inner sides of its turns engagingand guided by the four parallel sides of the tension members, a pair ofspring abutment discs at opposite ends of the spring, each disc providedwith a pair of narrow, intersecting slots extending at right angles toeach other in the form of a- Maltese cross and each slot containing atits outer end one of the four sides of the two tension members in springpressed engagement with the disc at said outer end, whereby each side isheld from outward movement at two points along its length, the innerfaces of the discs being engaged by opposite ends of the spring in theregion thereof external to the slots, the outer face of each discengaging its associated abutment and diametrically opposite points ofits peripheral edge engaged by the stops at the adjacent ends of thetension member whereby each disc is held to its seat provided by theabutment and stops by the spring, the crotch end of each tension memberhaving a Width less than the length of the slot which parallels it inthe adjacent disc whereby in assembling and in demounting the springassembly the crotch end of each tension member may be withdrawn throughthe disc which is adjacent thereto thus releasing the same from thespring and each slot having a length greater than the Width of the bentend of each tension member plus the diameter of the wire forming thetension member whereby each disc may be either hooked on to or unhookedfrom the disc adjacent its free end when free of the spring withoutnecessity of bending or otherwise modifying the preformed forms of thetension members.

2. A spring assembly comprising five preformed elements adapted to beassembled and demounted manually without changing the preformedconfiguration of the elements, said elements comprising two similarcompletely preformed wire tension members, each being of U-form havingsubstantially parallel and spaced apart sides connected at a crotch endwith the free ends bent relatively outward from each other, a coiledcompression spring encircling the midportion of the tension members, apair of spring abutment discs at opposite ends of the spring, each discprovided with a pair of long narrow intersecting slots, each slotcontaining at its outer end one of the four sides of the two tensionmembers in spring pressed engagement with the disc at said outer end andsaid slots acting to maintain the sides of the tension members incircumferentially spaced apart relation, the inner faces of the discsbeing engaged by opposite ends of the spring, the crotch end of eachtension member having a width less than the length of the slots topermit the crotch end of either tension member to pass freelytherethrough and each slot having a length to permit the passingtherethrough of the free ends of either tension member.

3. A spring assembly comprising five preformed elements, said elementsconsisting of a compression spring, a pair of U-shaped tension membershaving substantially parallel sides engaging the inner turns of thespring to form a core for the same and having outturned ends, a pair ofdiscs at opposite ends of the spring and through which the adjacentparts of the tension members are passed and said spring acting throughthe discs to maintain the same in engagement with the outturned ends,andsaid discs and tension members provided with coacting means forsecuring the sides of the tension members in their circumferentiallyspaced apart relation engaging the spring.

JULIUS E. PU'RWEET.

